Google has started alerting some advertisers regarding how phone numbers display in ads that call extensions will begin generating automatically as of 6th February, 2017.
The notice regarding this emailed to advertisers started going out on yesterday evening.
Below is the copy of full email.
In case if advertisers do not want to pay for calls directed to the phone number listed on their landing pages they will have to opt out of all automated extensions as Google already generates structured snippets, callouts and dynamic sitelinks. To opt out of this, select “Do not use specific automated extensions for this account” option which you can see at the bottom of the Automated extensions report from the Ad extensions tab in AdWords.